Electroosmotic pump and fluid-pumping system comprising the same

ABSTRACT

Provided are an electroosmotic pump, including: a membrane; a first electrode which is provided on one surface of the membrane, including a porous support including an insulator and an electrochemical reaction material formed on the porous support; and a second electrode which is provided on the other surface of the membrane, including a porous support including an insulator and an electrochemical reaction material formed on the porous support, and a fluid-pumping system including the electroosmotic pump.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/313,852, filed on Dec. 27, 2018 as the U.S. National Phase under 35U.S.C. § 371 of International Application PCT/KR2017/006343, filed Jun.16, 2017, now U.S. Pat. No. 11,015,583, which claims priority to KoreanPatent Application No. 10-2016-0081146, filed Jun. 28, 2016, which arehereby incorporated by reference in their entirety.

BACKGROUND Field

The present invention relates to an electroosmotic pump and afluid-pumping system including the electroosmotic pump.

Description of the Related Technology

An electroosmotic pump is a pump which utilizes the fluid transportphenomenon that occurs when a voltage is applied to both ends of acapillary tube or porous separation membrane. Accordingly, when a pumpis to be constituted using electroosmosis, electrodes for voltageapplication are essentially used at both ends of a capillary tube orporous separation membrane.

Conventionally, chemically-stable platinum was frequently used as anelectrode material. However, platinum has a low hydrogen overpotentialfor water, and thus hydrogen gas is generated at the cathode when apotential difference of a few volts or more is actually applied to bothends of a porous separation membrane, and the gas generation becomes afactor that limits commercialization of the electroosmotic pump.

The problem of gas generation normally occurring at electrodes has beenresolved by introducing materials which are capable of oxidation andreduction to the electrodes, instead of the electrolysis reaction ofwater, and silver (Ag)/silver oxide (AgO), MnO(OH), polyaniline, etc.are used as the material for the electrochemical reaction.

Meanwhile, the electrode used for the electroosmotic pump mustsimultaneously be able to cause an electrochemical reaction and allow aworking fluid (e.g., water) to pass through.

Since the electrode must simultaneously provide a site for anelectrochemical reaction and allow a working fluid to freely passthrough, a carbon paper and a carbon woven fabric that exhibit highporosity have been widely used for electrodes, and those electrodes,which are manufactured by a method of electrodeposition or coating of anelectrochemical reaction material (e.g., silver (Ag)/silver oxide (AgO),MnO(OH), polyaniline, etc.) to the surface of the carbon material havebeen widely used.

However, these electrodes which were manufactured by the method ofelectrodeposition or coating of an electrochemical reaction material toa porous carbon electrode (e.g., a carbon paper electrode or a carbonwoven-fabric electrode) have a very challenging problem in that, as theoperation of the electroosmotic pump is repeated, the electrochemicalreaction material electrodeposited or coated on the electrodes isconsumed and detached such that the carbon electrode surface is exposed,and a new electrochemical reaction (e.g., electrolysis of water) occurson the exposed carbon electrode surface as a side reaction therebyrapidly increasing power consumption of the electroosmotic pump. Whensuch a phenomenon occurs, in the case of the electroosmotic pump using abattery, the time available for its use is significantly reduced.

The amount of power required for the operation of a pump is an importantfactor in determining practical applicability when the pump is appliedto a patch-type drug delivery device to be attached to the human body ora wearable medical device.

Additionally, with a growing interest on the method of deliveringmedication by implanting a small pump inside the human body, interest inthe electroosmotic pump which can be stably operated without any sidereaction is gradually increasing, and accordingly, studies for theimprovement of stability, lifespan characteristics, and efficiency ofthe electroosmotic pump are underway.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

In an exemplary embodiment, the present invention provides anelectroosmotic pump in which no side reaction due to consumption ordetachment of the electrochemical reaction material occurs even after along-time operation and thus no subsequent increase in currentconsumption and power consumption occurs, thus having excellentstability, lifespan characteristics, and efficiency.

In another exemplary embodiment, the present invention provides afluid-pumping system including the electroosmotic pump.

In an exemplary embodiment, the present invention provides anelectroosmotic pump, which includes: a membrane; a first electrode whichis provided on one surface of the membrane, including a porous supportincluding an insulator and an electrochemical reaction material formedon the porous support; and a second electrode which is provided on theother surface of the membrane, including a porous support including aninsulator and an electrochemical reaction material formed on the poroussupport.

The insulator may include at least one selected from the groupconsisting of a ceramic not showing conductivity, a polymer resin notshowing conductivity, glass not showing conductivity, and a combinationthereof.

The ceramic not showing conductivity may include at least one selectedfrom the group consisting of rockwool, gypsum, ceramics, cement, and acombination thereof.

The polymer resin not showing conductivity may include at least oneselected from the group consisting of: a synthetic fiber, which isselected from the group consisting of polypropylene, polyethyleneterephthalate, polyacrylonitrile, and a combination thereof; a naturalfiber, which is selected from the group consisting of wool, cotton, anda combination thereof; a sponge; a porous material derived from abiological organism; and a combination thereof.

The glass not showing conductivity may include at least one selectedfrom the group consisting of glass wool, glass frit, porous glass, and acombination thereof.

The porous support may have a shape of a non-woven fabric, a wovenfabric, a sponge, or a combination thereof.

The porous support may have a pore size of about 0.1 μm to about 500 μm.

The porous support may have porosity of about 5% to about 95%.

The electrochemical reaction material may include at least one selectedfrom the group consisting of silver/silver oxide, silver/silverchloride, and a combination thereof.

In another exemplary embodiment, the present invention provides afluid-pumping system including the electroosmotic pump.

The electroosmotic pump according to an exemplary embodiment hasadvantages in that no side reaction due to the consumption or detachmentof the electrochemical reaction material occurs even after a long-timeoperation and thus no subsequent increase in current consumption andpower consumption occurs, thereby being able to improve stability, lifecharacteristics, and efficiency, while reducing manufacturing costbecause a high-cost carbon electrode (e.g., carbon paper electrode,carbon woven-fabric electrode, etc.) is not used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an electroosmotic pumpaccording to an exemplary embodiment of the present invention.

FIG. 2A and FIG. 2B are schematic diagrams illustrating reversibleelectrode reactions in an electroosmotic pump according to an exemplaryembodiment of the present invention, and subsequent movements of ionsand a fluid.

FIG. 3 is an exploded perspective view of an electroosmotic pumpaccording to an exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view of the electroosmotic pump illustratedin FIG. 3 .

FIG. 5 is an electron microscope image of an electrode manufacturedaccording to Example 1.

FIG. 6 is a current characteristic curve of the electroosmotic pumpmanufactured in Example 2 for a period of 14 hours.

FIG. 7 is a current characteristic curve of the electroosmotic pumpmanufactured in Comparative Example 2 for a period of 10 minutes.

FIG. 8 is a current characteristic curve of the electroosmotic pumpmanufactured in Comparative Example 2 for a period of 14 hours.

DETAILED DESCRIPTION OF CERTAIN ILLUSTRATIVE EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail so that those of ordinary skill in the art to whichthe present invention pertains can easily carry it out with reference toaccompanying drawings. However, the present invention may be embodied inmany different forms, and is not limited to these embodiments describedherein.

In the drawings, the thickness of layers, regions, etc., are exaggeratedfor clarity. Like reference numerals designate like elements throughoutthe specification. When a part of a layer, film, coating, etc. isreferred to as being “on” another constituent element, it includes notonly the case of “on top of” another constituent element but also thecase where another constituent element is disposed therebetween.

Throughout the specification, when a part “comprises” certainconstituent elements, it means that the part may include otherconstituent elements, without excluding other constituent elements,unless otherwise specifically indicated, and “combination” means mixing,polymerization, or copolymerization.

Hereinafter, the electroosmotic pump according to an exemplaryembodiment of the present invention will be explained referring to FIG.1 to FIG. 4 .

FIG. 1 is a schematic diagram illustrating an electroosmotic pumpaccording to an exemplary embodiment of the present invention.

Referring to FIG. 1 , the electroosmotic pump 100 includes a membrane11; a first electrode 13 which is provided on one surface of themembrane 11, including a porous support including an insulator and anelectrochemical reaction material formed on the porous support; and asecond electrode 15 which is provided on the other surface of themembrane 11, including a porous support including an insulator and anelectrochemical reaction material formed on the porous support.

The first electrode 13 and the second electrode 15 are connected to apower supply part 17. The first electrode 13 and the second electrode 15may be connected to the power supply part 17 by, for example, a leadwire, but the connecting means is not limited thereto as long as theycan be electrically connected.

The membrane 11 is installed in fluid pathway parts 19 and 19′ throughwhich fluid is moved, and it may have a porous structure to enable themovement of a fluid and ions therethrough.

The membrane 11 may be a frit-type membrane manufactured by sinteringspherical silica with heat, but the membrane is not limited thereto, andany material such as a porous silica or porous alumina that can cause anelectrokinetic phenomenon by a zeta potential may be used.

The spherical silica used in the formation of the membrane may have adiameter of about 20 nm to about 500 nm, specifically about 30 nm toabout 300 nm, and more specifically about 40 nm to about 200 nm. Whenthe diameter of the spherical silica is within the above range, theelectroosmotic pump may be able to generate a greater pressure.

The membrane 11 may have a thickness of about 20 μm to about 10 mm,specifically about 300 μm to about 5 mm, and more specifically about1000 μm to about 4 mm. When the thickness of the membrane 11 is withinthe above range, the membrane can exhibit sufficient strength towithstand a mechanical impact being applied during the manufacture, use,or storage of the electroosmotic pump, and it can also exhibit asufficient flow amount to be used as a pump for drug delivery.

The first electrode 13 and the second electrode 15 respectively includea porous support including an insulator and an electrochemical reactionmaterial formed on the porous support. In particular, the porous supportincluding an insulator which are included in the first electrode 13 andthe second electrode 15 respectively may be the same as or differentfrom each other, and the electrochemical reaction material which areincluded in the first electrode 13 and the second electrode 15respectively may be the same as or different from each other.

The first electrode 13 and the second electrode 15 may facilitateeffective movement of the fluid and ions by having a porous structure.

The insulator forming the porous support may include at least oneselected from the group consisting of a ceramic not showingconductivity, a polymer resin not showing conductivity, glass notshowing conductivity, and a combination thereof, but the insulator isnot limited thereto.

As such, when a porous support including an insulator is used in thefirst electrode 13 and the second electrode 15, the electrochemicalreaction material used in the first electrode 13 and the secondelectrode 15 is consumed or detached after a long-time operation of theelectroosmotic pump, and thus, even when the porous support is exposed,the side reaction (e.g., water electrolysis) that had conventionallyoccurred due to the exposure of carbon paper or carbon woven-fiber whenthe carbon paper or carbon woven-fiber were used does not occur, andthereby unnecessary current consumption and power consumption can beprevented. By doing so, an electroosmotic pump which has a stableoperation characteristic, excellent lifespan stability, excellentelectrical efficiency, and that can reduce manufacturing cost can beimplemented.

The ceramic not showing conductivity may include at least one selectedfrom the group consisting of rockwool, gypsum, ceramics, cement, and acombination thereof, and specifically at least one selected from thegroup consisting of rockwool, gypsum, and a combination thereof, but theceramic not showing conductivity is not limited thereto.

Meanwhile, the ceramic not showing conductivity may be, for example, asintered material of a ceramic powder or natural porous ceramic, but theceramic not showing conductivity is not limited thereto.

The polymer resin not showing conductivity may include at least oneselected from the group consisting of: a synthetic fiber, which isselected from the group consisting of polypropylene, polyethyleneterephthalate, polyacrylonitrile, and a combination thereof; a naturalfiber, which is selected from the group consisting of wool, cotton, anda combination thereof; a sponge; a porous material derived from abiological organism (e.g., bones of a biological organism); and acombination thereof, but the polymer resin not showing conductivity isnot limited thereto.

The glass not showing conductivity may include at least one selectedfrom the group consisting of glass wool, glass frit, porous glass, and acombination thereof, but the glass not showing conductivity is notlimited thereto.

The porous support may conventionally have a form of a non-woven fabric,woven fabric, sponge, or a combination thereof, but the form of theporous support is not limited thereto as long as the support hasporosity thus enabling transport of a fluid and ions.

The porous support may have a pore size of about 0.1 μm to about 500 μm,specifically about 5 μm to about 300 μm, and more specifically of about10 μm to about 200 μm. When the pore size of the porous support iswithin the above range, a fluid and ions can effectively move, and thusthe stability, lifespan characteristic, and efficiency of theelectroosmotic pump can be effectively improved.

The porous support may have porosity of about 5% to about 95%,specifically about 50% to about 90%, and more specifically about 60% toabout 80%. When the porosity of the porous support is within the aboverange, a fluid and ions can effectively move, and thus the stability,lifespan characteristic, and efficiency of the electroosmotic pump canbe effectively improved.

As the electrochemical reaction material, any material that can form apair of reactions where an anode and a cathode can give and takepositive ions (e.g., hydrogen ions (H⁺)) and simultaneously constitute areversible electrochemical reaction during the electrode reactions, suchas silver/silver oxide and silver/silver chloride, can be used.

Specifically, the electrochemical reaction material may include at leastone selected from the group consisting silver/silver oxide,silver/silver chloride, MnO(OH), polyaniline, polypyrrole,polythiophene, polythionine, a quinone-based polymer, and a combinationthereof.

When the electrochemical reaction material as described above is used,oxidation and reduction are possible by a method other than waterelectrolysis, and thus the stability, lifespan characteristic, andefficiency of the electroosmotic pump can be effectively improved.

The electrochemical reaction material may be formed by electrodepositionor coating on a porous support including the insulator using methodssuch as electroless plating, plating, vacuum deposition, coating, asol-gel process, etc., but the methods are not limited thereto, and theelectrochemical reaction material may be formed on a porous supportincluding the insulator using an appropriate method according to thekinds of the electrochemical reaction material being used.

The power supply part 17 is connected to the first electrode 13 and thesecond electrode 15 to provide power so that an electrochemical reactioncan occur in the first electrode 13 and the second electrode 15, and theelectrochemical reaction of the first electrode 13 and the secondelectrode 15 can occur by the transport of positive ions.

The power supply part 17 can alternately supply the polarity of avoltage to the first electrode 13 and the second electrode 15, and inparticular, what is meant by the power supply part 17 alternatelysupplying the polarity of a voltage may include the meaning that thecurrent is alternately supplied in opposite directions. By such aprocess, the electroosmotic pump 100 can generate a pressure (pumpingpower) by the movement of a fluid, and simultaneously, the consumptionand regeneration of the electrochemical reaction material of the firstelectrode 13 and the second electrode 15 can repeatedly occur.

For example, the power supply part 17 may include a DC voltage supplypart (not shown) that supplies a DC voltage to each of the firstelectrode 13 and the second electrode 15. Additionally, the power supplypart 17 may include a voltage direction conversion part (not shown) thatalternately converts the polarity of the DC voltage supplied to each ofthe first electrode 13 and the second electrode 15 at predeterminedtimes. From the above, it is possible to continuously change the voltageapplied to each of the first electrode 13 and the second electrode 15 toan opposite polarity at predetermined times.

The fluid pathway parts 19 and 19′ provide the movement pathway of afluid that moves in both directions with the membrane 11, the firstelectrode 13 and the second electrode 15 disposed therebetween.

In particular, the fluid pathway parts 19 and 19′ may have a containershape where a fluid is filled inside (e.g., a cylindrical shape), butthe shape is not limited thereto.

The fluid not only can fill in the fluid pathway parts 19 and 19′, butalso the membrane 11 and the first and second electrodes 13 and 15.

The fluid pathway parts 19 and 19′ may have an opening for the transferof pressure (pumping power). For example, the opening may be formed onany one space or both spaces of the spaces divided into two parts by themembrane 11 and the first and second electrodes 13 and 15, and therebyprovide the pressure (pumping power) by the movement of a fluid to theoutside.

FIG. 2A and FIG. 2B are schematic diagrams illustrating reversibleelectrode reactions in an electroosmotic pump according to an exemplaryembodiment of the present invention, and subsequent movements of ionsand a fluid.

Referring to FIG. 2A and FIG. 2B, when a voltage is differently suppliedto the first electrode 13 and the second electrode 15, for example, witha difference in the polarity of a voltage through the power supply part17, a voltage difference occurs between the first electrode 13 and thesecond electrode 15.

By such a voltage difference, as a result of an electrode reaction,positive ions (M^(x+)) are produced in the anode, and as the positiveions (M^(x+)) move toward the cathode, they move along with a fluidthereby generating a fluid movement amount and a pressure (pumpingpower).

When power is supplied to the first electrode 13 and the secondelectrode 15 through the power supply part 17, the anode and the cathodecan be changed by alternately supplying the polarity of a voltage, andas a result, the movement direction of ions and a fluid, and thedirection of the pressure (pumping power) and the fluid amount, can bechanged.

When the role of the electrode which had served as an anode is changedto serve as a cathode due to the alternating supply of the voltagepolarity, the electrochemical reactive material which was consumed whenthe electrode was used as an anode can be recovered as the electrode isused as a cathode, and vice versa, thereby enabling the continuousoperation of the electroosmotic pump.

Taking a case where a silver/silver oxide is used as an electrochemicalreaction material and an aqueous solution is used as a fluid as anexample, a reaction as shown in Reaction Scheme 1 occurs in an anode anda reaction as shown in Reaction Scheme 2 occurs in a cathode. In thiscase, the positive ions which move are hydrogen ions (H⁺), and hydrogenions (H⁺) have a relatively rapid speed of ion transport and thus thetransport speed of the fluid which moves along with the ions can berapid as well, thus being able to effectively improve the performance ofthe electroosmotic pump 100.Ag(s)+H₂O→Ag₂O(s)→2H⁺+2e ⁻  [Reaction Scheme 1]Ag₂O(s)+2H⁺+2e ⁻→Ag(s)+H₂O  [Reaction Scheme 2]

In a case where a material other than the silver/silver oxide is used inthe first electrode 13 and second electrode 15 as an electrochemicalreaction material and a material other than an aqueous solution is usedas a fluid, it is natural that the oxidation/reduction reaction schememay vary accordingly, and the positive ions being produced andtransported may vary.

FIG. 3 is an exploded perspective view of an electroosmotic pumpaccording to an exemplary embodiment of the present invention, and FIG.4 is a cross-sectional view of the electroosmotic pump illustrated inFIG. 3 .

Referring to FIG. 3 and FIG. 4 , the membrane 11 may be in the form of adisc. In particular, a coating material, a barrier sheet, an adhesivesheet, etc. may be bonded onto the external circumferential surface ofthe membrane 11 to prevent fluid leakage.

Additionally, the first electrode 13 and second electrode 15 may have adisc shape so as to correspond to the shape of the membrane 11, and inparticular, a coating material, a barrier sheet, an adhesive sheet, etc.may also be bonded onto the external circumferential surface of thefirst electrode 13 and the second electrode 15 to prevent fluid leakage.

The first fluid pathway part (19, see FIG. 1 ) may include a first cap33 of the hollow space to be bonded to the first electrode 13.

Additionally, the second fluid pathway part (19′, see FIG. 1 ) mayinclude a second cap 53 of the hollow space to be bonded to the secondelectrode 15.

Between the two ends of the first cap 33 and the second cap 53, the endwhere the first electrode 13 and the second electrode 15 are located andthe end which is located at the opposite end may be connected to a firsttube 40 and a second tube 40′, where a fluid can be transported.

The first tube 40 and second tube 40′ may be, for example, siliconetubes, but the tube material is not limited thereto.

The electroosmotic pump 100 may include a first contact strip 31 whichis to be integrated into the external circumferential surface of thefirst electrode 13.

Additionally, the electroosmotic pump 100 may include a second contactstrip 51 which is to be integrated into the external circumferentialsurface of the second electrode 15.

The first contact strip 31 and the second contact strip 51 may each beconnected to the power supply part 17, and thereby deliver a voltage orcurrent to the first electrode 13 and the second electrode 15,respectively.

The first contact strip 31 and the second contact strip 51 may include aconductive material. Specifically, first contact strip 31 and the secondcontact strip 51 may include silver (Ag), copper (Cu), etc., but theelements are not limited thereto.

The first contact strip 31 and the second contact strip 51, as shown inFIG. 3 , may be in a circular form where the first electrode 13 and thesecond electrode 15 each external circumferential surface are integratedthereinto, but the form is not limited thereto.

In another exemplary embodiment, the present invention provides a fluidpumping system including the electroosmotic pump. The fluid pumpingsystem may be formed in a structure that is generally used in the art,and thus specific details are omitted herein.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail withreference to examples and comparative examples. However, these examplesand comparative examples are for illustrative purposes only and are notintended to limit the scope of the present invention.

EXAMPLES Example 1: Preparation of Polyethylene Terephthalate (PET)Non-Woven Fabric Electrode Coated with Silver (Ag)

10 g of polyethylene terephthalate non-woven fabric (Huvis, LMF degree)with a thickness of 0.2 mm was washed with an aqueous NaOH solution (1.6g NaOH/100 mL water) at room temperature for 30 minutes, washed severaltimes with distilled water, conditioned with an aqueous solution ofpolyethylene glycol (PEG 1000, 0.08 g polyethylene glycol/100 mL water),and washed again with distilled water.

While repeating stirring and washing, the resultant was subjected to asensitization process using SnCl₂ (0.8 g SnCl₂/100 mL water) for 5minutes and then to an activation process using PdCl₂ (0.04 g PdCl₂/100mL water) for 30 minutes. Then, the resultant was subjected to anacceleration process using a 10% aqueous HCl solution at roomtemperature for 30 minutes and then washed with distilled water.

The polyethylene terephthalate non-woven fabric, which underwentpretreatment processes, was put in a silver solution composed of silvernitrate, sodium hydroxide, and ammonia, and a reducing solution wheresodium hypophosphite were dissolved, and subjected to electrolessplating for 1 hour in total.

The polyethylene terephthalate non-woven fabric coated with silver wasanodized under a potential difference of 2 V at both ends using a silverplate as a counter electrode so as to produce Ag₂O particles on thesurface, and the same was used as a porous electrode for theelectroosmotic pump.

FIG. 5 is an electron microscope image of an electrode manufacturedaccording to Example 1.

By observing the morphology of the silver and silver oxide coated on thepolyethylene terephthalate non-woven fabric from FIG. 5 , it can beconfirmed that the silver/silver oxide is very uniformly distributedwhile maintaining overall porosity.

Example 2: Preparation of Electroosmotic Pump

An electroosmotic pump having the same shape as those of FIG. 3 and FIG.4 was prepared. The membrane was prepared by loading spherical silica(diameter 300 nm) in a mold to be formed into a coin shape with anexterior diameter of 8 mm and a thickness of 1 mm by applying a load of1 ton and sintering at 700° C.

The electrodes prepared in Example 1 were processed into a circularshape having an exterior diameter of 8 mm and stacked up on both sidesof the membrane, and subsequently, a contact strip and a cap wereinstalled, and the exterior was sealed using an epoxy resin.

Comparative Example 1: Preparation of Carbon Paper Electrode Coated withSilver (Ag)

Carbon paper with a thickness of 0.28 mm (Toray, Japan, THP-H-090) wassubjected to plasma treatment in a low pressure plasma device for 1hour.

The plasma-treated carbon paper was installed in an electroplating tankand coated with silver at a current density of 30 mA/cm² for 10 minutes.The silver-coated carbon paper was transferred into a differentelectroplating tank and anodized at a current of 15 mA/cm² such that anelectrode where an Ag₂O layer was coated on the surface was prepared.

The electrode was prepared as a circular electrode with an exteriordiameter of 8 mm.

Comparative Example 2: Preparation of Electroosmotic Pump

An electroosmotic pump was prepared in the same manner as in Example 2,except that the electrodes prepared in Comparative Example 1 were usedinstead of the electrodes prepared in Example 1.

Test Example 1: Evaluation of Performance of Electroosmotic Pump

A potential difference of 2 V was applied to each of the two electrodesof the electroosmotic pumps prepared in Example 2 and ComparativeExample 2 at alternate intervals of 1 minute for 10 minutes, and theresulting current response characteristics were evaluated. Additionally,a potential difference of 2 V was applied to each of the two electrodesof the electroosmotic pumps prepared in Example 2 and ComparativeExample 2 at alternate intervals of 1 minute for 14 hours, and theresulting current response characteristics were evaluated.

The current characteristic curve of the electroosmotic pump prepared inExample 2 for a period of 14 hours is shown in FIG. 6 , the currentcharacteristic curve of the electroosmotic pump prepared in ComparativeExample 2 for a period of 10 minutes is shown in FIG. 7 , and thecurrent characteristic curve of the electroosmotic pump prepared inComparative Example 2 for a period of 14 hours is shown in FIG. 8 ,respectively.

According to what is shown in FIG. 6 , it was confirmed that, in theelectroosmotic pump prepared in Example 2, a constant current flow wasmaintained even after a long-time operation.

Meanwhile, according to what is shown in FIGS. 7 and 8 , in theelectroosmotic pump prepared in Comparative Example 2, the current flowtherein was maintained for about 10 minutes, but the current rapidlyincreased as the operation time increased thereby increasing the powerconsumption. From the above results, it was confirmed that, in theelectroosmotic pump prepared in Comparative Example 2, as the operationtime became longer, the carbon paper was exposed due to the consumptionor detachment of the silver/silver oxide (i.e., the electrochemicalreaction material), and the exposed carbon paper caused a side reaction(e.g., electrolysis of water) thereby rapidly increasing the powerconsumption of the electroosmotic pump.

As a result, it was confirmed that the electroosmotic pump prepared inExample 2 was superior with respect to stability, lifespancharacteristic, and efficiency, compared to that of the electroosmoticpump prepared in Comparative Example 2.

Although the preferred embodiments of the present invention have beendescribed above, the present invention is not limited thereto, and itwill be apparent to those skilled in the art that various changes andmodifications may be made within the scope of the claims, the detaileddescription of the invention, and the accompanying drawings.

As described above, the electroosmotic pump according to the presentinvention includes electrodes containing a porous support including aninsulator and an electrochemical reaction material formed on the poroussupport, and as a result, even after a long-time operation, neither aside reaction due to the consumption or detachment of theelectrochemical reaction material nor a subsequent increase in currentconsumption or power consumption occurs, thereby enabling theimprovement of stability, lifespan characteristics, and efficiency.

What is claimed is:
 1. An electroosmotic pump, comprising: at least afluid pathway part formed in a line shape; a membrane having a porousstructure and being in the fluid pathway part; a first electrode havingporosity, being in the fluid pathway part and disposed on the membrane,the first electrode comprising a first insulating porous support and afirst electrochemical reaction material coated on the first insulatingporous support; and a second electrode having porosity, being in thefluid pathway part and disposed on the membrane, the second electrodecomprising a second insulating porous support and a secondelectrochemical reaction material coated on the second insulating poroussupport, wherein the first electrochemical reaction material issubstantially uniformly distributed on the first insulating poroussupport, wherein the second electrochemical reaction material issubstantially uniformly distributed on the second insulating poroussupport, and wherein fluid in the fluid pathway part is moved throughthe membrane, the first electrode and the second electrode.
 2. Theelectroosmotic pump of claim 1, wherein one or both of the first andsecond insulating porous supports comprise an electrically insulatingceramic, an electrically insulating polymer resin, an electricallyinsulating glass, or a combination thereof.
 3. The electroosmotic pumpof claim 2, wherein the electrically insulating ceramic comprisesrockwool, gypsum, ceramic, cement, or a combination thereof.
 4. Theelectroosmotic pump of claim 2, wherein the electrically insulatingpolymer resin comprises: a synthetic fiber selected from the groupconsisting of polypropylene, polyethylene terephthalate,polyacrylonitrile, or a combination thereof; a natural fiber selectedfrom the group consisting of wool, cotton, or a combination thereof; asponge; a porous material derived from a biological organism; or acombination thereof.
 5. The electroosmotic pump of claim 2, wherein theelectrically insulating glass comprises glass wool, glass frit, porousglass, or a combination thereof.
 6. The electroosmotic pump of claim 1,wherein one or both of the first and second insulating porous supportsare in the form of a non-woven fabric, a woven fabric, sponge, or acombination thereof.
 7. The electroosmotic pump of claim 1, wherein oneor both of the first and second insulating porous supports have poreshaving a size of 0.1 μm to 500 μm.
 8. The electroosmotic pump of claim1, wherein one or both of the first and second insulting porous supportshave a porosity of 5% to 95%.
 9. The electroosmotic pump of claim 1,wherein one or both of the first and second electrochemical reactionmaterials comprise silver/silver oxide, silver/silver chloride, or acombination thereof.
 10. A fluid-pumping system comprising theelectroosmotic pump according to claim
 1. 11. A fluid-pumping systemcomprising the electroosmotic pump according to claim
 2. 12. Afluid-pumping system comprising the electroosmotic pump according toclaim
 3. 13. A fluid-pumping system comprising the electroosmotic pumpaccording to claim
 4. 14. A fluid-pumping system comprising theelectroosmotic pump according to claim
 5. 15. A fluid-pumping systemcomprising the electroosmotic pump according to claim
 6. 16. Afluid-pumping system comprising the electroosmotic pump according toclaim
 7. 17. A fluid-pumping system comprising the electroosmotic pumpaccording to claim
 8. 18. A fluid-pumping system comprising theelectroosmotic pump according to claim 9.